ospack: fix keyring package field typo

`debos` supports keyring-package in debootstrap action, but no
keyringpackage. This change syncs to proper field key.

Signed-off-by: Héctor Orón Martínez <hector.oron@collabora.co.uk>
Reviewed-by: Andrew Shadura <andrew.shadura@collabora.co.uk>
Differential Revision: https://phabricator.apertis.org/D7642

apertis-ospack.yaml

@@ -15,7 +15,7 @@ actions:
       - target
     mirror: {{ $mirror }}
     variant: minbase
-    keyringpackage: apertis-archive-keyring
+    keyring-package: apertis-archive-keyring
     merged-usr: false
 
   # Add image version information